Can dexmedetomidine be a safe and efficacious sedative agent in post-cardiac surgery patients? a meta-analysis

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Authors�� response

We thank Gu for his comments. Indeed, our results indicate that sedation with dexmedetomidine
is associated with shorter length of mechanical ventilation and lower risk of delirium
following cardiac surgery. Further, dexmedetomidine may decrease the risk of postoperative
ventricular tachycardia and hyperglycemia, and not increase length of hospital stay
and mortality at hospital discharge. [1] Thus, we hypothesized that dexmedetomidine
would be a safe and efficacious sedative agent in cardiac surgical patients.
Please note that we have listed several limitations of this study at the end of the
manuscript. [1] First, different goals of ideal sedation, and different diagnosis
method may not result in the widespread utilization of our results. Second, considering
the high cost of dexmedetomidine, additional cost-effective studies are warranted.
To enable adequate cost comparisons, proper drug-related cost must be well-defined
during clinical study designs, which is generally not the case. However, Gu raised
an interesting concern with regard to the lack of high quality randomized controlled
studies, which could underscore the value of adequate patient selection for the safe
use of dexmedetomidine following cardiac surgery.

To the Editor:
I read with interest the paper published in Critical Care by Lin and colleagues, who
investigated the effectiveness and safety of dexmedetomidine as a sedative agent in
post-cardiac surgery patients [1]. I congratulate the authors on their interesting
and important work on this topic. Nevertheless, some concerns need to be discussed.
First, inclusion/exclusion criteria: a) In Materials and methods, only randomized
controlled trial, non-random controlled trial or cohort study was included this meta-analysis.
But a case-control study [2] was also included in Table 2. b) Why exclude the non-English
language studies? Though I appreciate the difficulty of assessing a manuscript written
in a language you do not speak or write, there is no scientific reason for excluding
such manuscripts. It was possible that the exclusion of non-English language studies
may lead to bias in effect size. The authors should give a more detailed description
of the inclusion/exclusion criteria.
Second, outcomes: a) The meta-analysis indicated that there were no significant differences
in intensive care unit stay, hospital stay, and morphine equivalents. In fact, these
results are not conclusive inasmuch as they are not adequately powered to examine
the effect of dexmedetomidine on these endpoints. They were not regarded as the primary
outcome and were the only clinically significant endpoints consistently reported in
some of the studies included in this meta-analysis. b) Although many outcomes were
assessed, there are other equally important variables that can determine the use of
dexmedetomidine as a sedative agent (all-cause mortality, myocardial infarction or
ischemia, etc.).
Third, the real question is why dexmedetomidine is not the ubiquitous sedative agent
in post-cardiac surgery patients if it is so good? However, there are many other reasons
why it is not widely used and none of these are presented in this review. First, there
is no mention of the cost of an ampoule of dexmedetomidine versus other medications.
Most institutions cannot split an ampoule of dexmedetomidine among patients and in
fact, restrict the use of this medication altogether in the hospital because it is
very expensive, far more expensive than other medications. That being the case, how
do the authors justify dexmedetomidine? Second, these comparative studies that are
cited in the meta-analysis are flawed. Most of them were non-randomized and poor-quality.
In conclusion, the use of dexmedetomidine may need practical considerations in post-cardiac
surgery patients.
References
1. Yiyun Lin, Bin He, Jian Chen, Zhinong Wang: Can dexmedetomidine be a safe and efficacious
sedative agent in post-cardiac surgery patients: a meta-analysis? Critical Care 2012,
16:R169.
2. Reichert MG, Jones WA, Royster RL, Slaughter TF, Kon ND, Kincaid EH: Effect of
a dexmedetomidine substitution during a nationwide propofol shortage in patients undergoing
coronary artery bypass graft surgery. Pharmacotherapy 2011, 31:673-677.